Radio receiver utilizing a single analog to digital converter

ABSTRACT

A radio receiver includes a low noise amplifier, intermediate frequency mixing stage, complex bandpass filter, a single analog to digital converter, a 1 st  digital mixing module, and a 2 nd  digital mixing module. The low noise amplifier is operably coupled to amplify a modulated radio frequency (RF) signal to produce an amplified modulated RF signal. The intermediate frequency mixing stage is operably coupled to mix the amplified modulated RF signal with a local oscillation to produce a modulated IF signal. The complex bandpass filter filters an I and Q component of the modulated IF signal to produce a filtered IF signal. The single analog to digital converter is operably coupled to convert the filtered IF signal into a digital IF signal. The 1 st  and  2   nd  mixing modules each receive the digital IF signal and mix the digital IF signal with an in-phase and quadrature digital local oscillation to produce a 1 st  baseband signal component and a 2 nd  baseband signal component.

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates generally to communication systems andmore particularly to radio receivers used within such communicationsystems.

BACKGROUND OF THE INVENTION

[0002] Communication systems are known to support wireless and wirelined communications between wireless and/or wire lined communicationdevices. Such communication systems range from national and/orinternational cellular telephone systems to the Internet topoint-to-point in-home wireless networks. Each type of communicationsystem is constructed, and hence operates, in accordance with one ormore communication standards. For instance, wireless communicationsystems may operate in accordance with one or more standards including,but not limited to, IEEE 802.11, Bluetooth, advanced mobile phoneservices (AMPS), digital AMPS, global system for mobile communications(GSM), code division multiple access (CDMA), local multi-pointdistribution systems (LMDS), multi-channel-multi-point distributionsystems (MMDS), and/or variations thereof.

[0003] Depending on the type of wireless communication system, awireless communication device, such as a cellular telephone, two-wayradio, personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel or channels (e.g., one of the pluralityof radio frequency (RF) carriers of the wireless communication system)and communicate over that channel. For indirect wireless communications,each wireless communication device communicates directly with anassociated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe internet, and/or via some other wide area network.

[0004] For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the transmitter converts datainto RF signals by modulating the data in accordance with the particularwireless communication standard to an RF carrier directly or in one ormore intermediate frequency stages to produce the RF signals.

[0005] As is also known, the receiver receives RF signals, removes theRF carrier frequency from the RF signals via one or more intermediatefrequency (IF) stages to produce analog baseband signals, converts theanalog low IF signals into digital low IF signals, and demodulates thedigital baseband signals in accordance with a particular wirelesscommunication standard to recapture the transmitted data. The analog lowIF signals include an in-phase (I) component and a quadrature (Q)component. As such, the receiver includes two analog to digital convertsto convert the analog I and Q signals into digital I and Q signals.

[0006] The demands for enhanced performance smaller sizes, lower powerconsumption, and reduced costs of wireless communication devices areincreasing. As such, stringent performance and size criteria are placedon the components comprising the wireless communication device. Forexample, the performance requirements for the analog to digital convertsto convert the analog I and Q signal components into digital signals arequite stringent requiring a complex circuit implementation. Such acomplex circuit implementation requires a relatively large silicon area(i.e., integrated circuit real estate) and consumes a relativelysignificant amount of power.

[0007] Therefore, a need exists for reducing size and power consumptionof the analog to digital conversion process in radio receivers.

SUMMARY OF THE INVENTION

[0008] The radio receiver including a single analog to digital converteras disclosed herein substantially meets these needs and others. Such aradio receiver includes a low noise amplifier, intermediate frequencymixing stage, complex bandpass filter, a single analog to digitalconverter, a 1^(st) digital mixing module, and a 2^(nd) digital mixingmodule. The low noise amplifier is operably coupled to amplify amodulated radio frequency (RF) signal to produce an amplified modulatedRF signal. The modulated RF signal may be modulated in accordance withany one of a plurality of wireless communication standards including,but not limited to, Bluetooth, 802.11a, 802.11b, et cetera.

[0009] The intermediate frequency mixing stage is operably coupled tomix the amplified modulated RF signal with a local oscillation toproduce a modulated IF signal. The local oscillation is selected to beof a frequency such that the difference between the frequency of the RFsignal and the frequency of the local oscillation produces theintermediate frequency.

[0010] The complex bandpass filter filters an I and Q component of themodulated IF signal to produce a filtered IF signal. The complexbandpass filter filters the I and Q components in such a way to producea single filtered IF signal, which contains the I and Q information.

[0011] A single analog to digital converter is operably coupled toconvert the filtered IF signal into a digital IF signal. The 1^(st) and2^(nd) mixing modules each receive the digital IF signal and mix thedigital IF signal with an in-phase and quadrature digital localoscillation to produce a 1^(st) baseband signal component and a 2^(nd)baseband signal component. For example, the 1^(st) baseband signalcomponent may be an in-phase baseband digital signal and the 2^(nd)baseband signal component may be a quadrature baseband signal.

[0012] In an alternative embodiment, an apparatus for digitalintermediate frequency to baseband conversion of a single digital IFsignal includes processing that enables the apparatus to receive asingle digital IF signal that corresponds to a modulated radio frequencysignal. The processing further enables the apparatus to mix the singledigital IF signal with a 1^(st) digital local oscillation to produce a1^(st) digitally mixed signal. The processing further allows theapparatus to mix the single digital IF signal with a 2^(nd) digitallocal oscillation to produce a 2^(nd) digitally mixed signal. Theprocessing further allows the apparatus to perform a decimation filterupon the 1^(st) and 2^(nd) digitally mixed signals to produce 1^(st) and2^(nd) baseband signal components. The 1^(st) and 2^(nd) baseband signalcomponents may be further processed to recapture transmitted data.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 illustrates a schematic block diagram of a communicationsystem in accordance with the present invention;

[0014]FIG. 2 illustrates a schematic block diagram of a wirelesscommunication device in accordance with the present invention;

[0015]FIG. 3 illustrates a schematic block diagram that furtherillustrates the receiver section of the wireless communication device ofFIG. 2;

[0016]FIG. 4 illustrates a schematic block diagram of an analog todigital converter in accordance with the present invention;

[0017]FIG. 5 illustrates a schematic block diagram of a low pass filterin accordance with the present invention; and

[0018]FIG. 6 illustrates a logic diagram of a method for processingintermediate frequency signals from a single analog to digital converterin accordance with the present invention.

DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT

[0019]FIG. 1 illustrates a schematic block diagram of a communicationsystem 10 that includes a plurality of base stations and/or accesspoints 12-16, a plurality of wireless communication devices 18-32 and anetwork hardware component 34. The wireless communication devices 18-32may be laptop host computers 18 and 26, personal digital assistant hosts20 and 30, personal computer hosts 24 and 32 and/or cellular telephonehosts 22 and 28. The details of the wireless communication devices willbe described in greater detail with reference to FIG. 2.

[0020] The base stations or access points 12 are operably coupled to thenetwork hardware 34 via local area network connections 36, 38 and 40.The network hardware 34, which may be a router, switch, bridge, modem,system controller, et cetera provides a wide area network connection 42for the communication system 10. Each of the base stations or accesspoints 12-16 has an associated antenna or antenna array to communicatewith the wireless communication devices in its area. Typically, thewireless communication devices register with a particular base stationor access point 12-14 to receive services from the communication system10. For direct connections (i.e., point-to-point communications),wireless communication devices communicate directly via an allocatedchannel.

[0021] Typically, base stations are used for cellular telephone systemsand like-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio and/or is coupled to a radio. The radio includes a highlylinear amplifier and/or programmable multi-stage amplifier as disclosedherein to enhance performance, reduce costs, reduce size, and/or enhancebroadband applications.

[0022]FIG. 2 illustrates a schematic block diagram of a wirelesscommunication device that includes the host device 18-32 and anassociated radio 60. For cellular telephone hosts, the radio 60 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 60 may be built-in or anexternally coupled component.

[0023] As illustrated, the host device 18-32 includes a processingmodule 50, memory 52, radio interface 54, input interface 58 and outputinterface 56. The processing module 50 and memory 52 execute thecorresponding instructions that are typically done by the host device.For example, for a cellular telephone host device, the processing module50 performs the corresponding communication functions in accordance witha particular cellular telephone standard.

[0024] The radio interface 54 allows data to be received from and sentto the radio 60. For data received from the radio 60 (e.g., inbounddata), the radio interface 54 provides the data to the processing module50 for further processing and/or routing to the output interface 56. Theoutput interface 56 provides connectivity to an output display devicesuch as a display, monitor, speakers, et cetera such that the receiveddata may be displayed. The radio interface 54 also provides data fromthe processing module 50 to the radio 60. The processing module 50 mayreceive the outbound data from an input device such as a keyboard,keypad, microphone, et cetera via the input interface 58 or generate thedata itself. For data received via the input interface 58, theprocessing module 50 may perform a corresponding host function on thedata and/or route it to the radio 60 via the radio interface 54.

[0025] Radio 60 includes a host interface 62, digital receiverprocessing module 64, a single analog-to-digital converter 66, a complexbandpass filter 68, IF mixing stage 70, a receiver filter 71, a lownoise amplifier 72, a transmitter filter 73, local oscillation module74, memory 75, digital transmitter processing module 76, atransmitter/receiver switch 77, digital-to-analog converter 78,filtering/gain module 80, IF mixing stage 82, power amplifier 84, and anantenna 86. The antenna 86 may be a single antenna that is shared by thetransmit and receive paths as regulated by the Tx/Rx switch 77, or mayinclude separate antennas for the transmit path and receive path. Theantenna implementation will depend on the particular standard to whichthe wireless communication device is compliant.

[0026] The digital receiver processing module 64 and the digitaltransmitter processing module 76, in combination with operationalinstructions stored in memory 75, execute digital receiver functions anddigital transmitter functions, respectively. The digital receiverfunctions include, but are not limited to, digital intermediatefrequency to baseband conversion, demodulation, constellation demapping,decoding, and/or descrambling. The digital transmitter functionsinclude, but are not limited to, scrambling, encoding, constellationmapping, modulation, and/or digital baseband to IF conversion. Thedigital receiver and transmitter processing modules 64 and 76 may beimplemented using a shared processing device, individual processingdevices, or a plurality of processing devices. Such a processing devicemay be a microprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on operational instructions. The memory 75may be a single memory device or a plurality of memory devices. Such amemory device may be a read-only memory, random access memory, volatilememory, non-volatile memory, static memory, dynamic memory, flashmemory, and/or any device that stores digital information. Note thatwhen the processing module 64 and/or 76 implements one or more of itsfunctions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory storing the corresponding operationalinstructions is embedded with the circuitry comprising the statemachine, analog circuitry, digital circuitry, and/or logic circuitry.The memory 75 stores, and the processing module 64 and/or 76 executes,operational instructions corresponding to at least some of the functionsillustrated in FIGS. 3-6.

[0027] In operation, the radio 60 receives outbound data 94 from thehost device via the host interface 62. The host interface 62 routes theoutbound data 94 to the digital transmitter processing module 76, whichprocesses the outbound data 94 in accordance with a particular wirelesscommunication standard (e.g., IEEE802.11a, IEEE802.11b, Bluetooth, etcetera) to produce digital transmission formatted data 96. The digitaltransmission formatted data 96 will be a digital base-band signal or adigital low IF signal, where the low IF typically will be in thefrequency range of one hundred kilohertz to a few megahertz.

[0028] The digital-to-analog converter 78 converts the digitaltransmission formatted data 96 from the digital domain to the analogdomain. The filtering/gain module 80 filters and/or adjusts the gain ofthe analog signal prior to providing it to the IF mixing stage 82. TheIF mixing stage 82 directly converts the analog baseband or low IFsignal into an RF signal based on a transmitter local oscillation 83provided by local oscillation module 74. The power amplifier 84amplifies the RF signal to produce outbound RF signal 98, which isfiltered by the Tx filter 73. The antenna 86 transmits the outbound RFsignal 98 to a targeted device such as a base station, an access pointand/or another wireless communication device.

[0029] The radio 60 also receives an inbound RF signal 85 via theantenna 86, which was transmitted by a base station, an access point, oranother wireless communication device. The antenna 86 provides theinbound RF signal 85 to the Rx filter 71 via the Tx/Rx switch 77, wherethe Rx filter 71 bandpass filters the inbound RF signal 85. The Rxfilter 71 provides the filtered RF signal to low noise amplifier 72,which amplifies the signal 88 to produce an amplified inbound RF signal.The low noise amplifier 72 provide the amplified inbound RF signal tothe IF mixing module 70, which directly converts the amplified inboundRF signal into an inbound low IF signal based on a receiver localoscillation 81 provided by local oscillation module 74. The downconversion module 70 provides the inbound low IF signal to the complexbandpass filter 68. The complex bandpass filter 68 may be of the typedisclosed in copending patent application entitled “Adaptive RadioTransceiver with Filtering” having a serial number of Ser. No.09/692,420 and a filing date of Oct.19, 2000. In general, the complexbandpass filter 68 filters analog I and Q components to produce a singlecomplex analog signal (e.g., a filtered IF signal 88) that retains theinformation of the I and Q components.

[0030] The single analog-to-digital converter 66 converts the filteredinbound low IF signal from the analog domain to the digital domain toproduce digital reception formatted data 90. The digital receiverprocessing module 64 decodes, descrambles, demaps, and/or demodulatesthe digital reception formatted data 90 to recapture inbound data 92 inaccordance with the particular wireless communication standard beingimplemented by radio 60. The host interface 62 provides the recapturedinbound data 92 to the host device 18-32 via the radio interface 54.

[0031]FIG. 3 illustrates a schematic block diagram of a portion of theradio receiver of the wireless communication device of FIG. 2. Theportion illustrated includes the complex bandpass filter 68, the singleanalog to digital converter 66, the digital receiver processing module64 and memory 75. The complex bandpass filter 68, which may be apolyphase filter that filters an I component and a Q component of themodulated IF signal to produce a single filtered IF signal may bedescribed in co-pending patent application entitled ADAPTIVE RADIOTRANSCEIVER WITH FILTERING, having a serial number of Ser. No.09/692,420 and a filing date of Oct. 19, 2000. The complex bandpassfilter 68 provides the filtered IF signal 88 to the analog to digitalconverter 66. Note that the filtered IF signal 88 is a single signalthat contains I and Q information of the modulated IF signal 87.

[0032] The analog to digital converter 66 converts the filtered IFsignal 88 into a digital IF signal. The analog to digital converter 66,may be constructed in accordance with any type of analog to digitalconverter topology including continuous time Delta Sigma analog todigital converters, flash analog to digital converters. For instance, asillustrated in FIG. 4 and will be described below, the analog to digitalconverter 66 may be a continuous time Delta Sigma analog to digitalconverter.

[0033] The digital receiver processing module 64 is configured and/orconstructed to include a 1^(st) digital mixing module 100, a 2^(nd)digital mixing module 102, a direct digital frequency synthesizer (DDFS)104, and a digital data recovery module 106. The 1^(st) digital mixingmodule 100 includes a digital mixer 112, a low pass decimation filter108 and a digital gain control module 110. The low pass decimationfilter 108 includes a low pass filter 114, which may be implemented asillustrated in FIG. 5, and a down sampling module 116. The 2^(nd)digital mixing module 102 includes a digital mixer 122, a low passdecimation filter 118, and a digital gain control module 120. The lowpass decimation filter 118 includes a low pass filter 124, which may beimplemented as illustrated in FIG. 5, and a down sampling module 126.

[0034] In operation, the analog to digital converter 66 provides thedigital IF signal to the 1^(st) digital mixing module and to the 2^(nd)digital mixing module. Within the 1^(st) digital mixing module 100,digital mixer 112 mixes the digital IF signal with an in-phase digitallocal oscillation, which is produced by the direct digital frequencysynthesizer 104, to produce a 1^(st) mixed signal at baseband. Note thatutilizing a lookup table may perform the multiplication performed by thedigital mixer via the direct digital frequency synthesizer. The low passdecimation filter 108 processes the 1^(st) mixed signal via the low passfilter 114 and the down sampling module 116 to produce a decimated mixedsignal. The down sampling module 116 may be a down convert by 4 modulesuch that the resulting rate of the decimated mixed signal is ¼^(th) ofthe rate of the 1^(st) mixed signal.

[0035] The digital gain control module 110 adjusts the magnitude of thedecimated mixed signal to produce the 1 ^(st) baseband signal component128. The gain control module 110 amplifies the baseband signal, i.e.,the output of the low pass decimation filter 108, to a level appropriatefor baseband processing by the digital data recovery module 106. Theappropriate level is at least partially dependent on the particularmodulation scheme prescribed by the corresponding wireless communicationstandard, the supply voltages of the radio frequency integrated circuitembodying the radio receiver of FIG. 3, and/or sensitivity of thecircuitry within the digital data recovery module 106.

[0036] Within the 2^(nd) digital mixing module 102, digital mixer 122mixes the digital IF signal with a quadrature digital local oscillation,which is produced by the direct digital frequency synthesizer 104, toproduce a 2^(nd) mixed signal at baseband. Note that utilizing a lookuptable may perform the multiplication performed by the digital mixer viathe direct digital frequency synthesizer. The low pass decimation filter118 processes the 2^(nd) mixed signal via the low pass filter 124 andthe down sampling module 126 to produce a decimated mixed signal. Thedown sampling module 126 may be a down convert by 4 module such that theresulting rate of the decimated mixed signal is ¼^(th) of the rate ofthe 2^(nd) mixed signal.

[0037] The digital gain control module 120 adjusts the magnitude of thedecimated mixed signal to produce the 2^(nd) baseband signal component130. The gain control module 120 amplifies the baseband signal, i.e.,the output of the low pass decimation filter 118, to a level appropriatefor baseband processing by the digital data recovery module 106. Theappropriate level is at least partially dependent on the particularmodulation scheme prescribed by the corresponding wireless communicationstandard, the supply voltages of the radio frequency integrated circuitembodying the radio receiver of FIG. 3, and/or sensitivity of thecircuitry within the digital data recovery module 106.

[0038] The digital data recovery module 106 receives the 1^(st) basebandsignal component 128 and the 2^(nd) baseband signal component 130 andproduces therefrom inbound data 92. The digital data recovery module 106decodes the 1^(st) and 2^(nd) baseband signal components in accordancewith the particular wireless communication standard being implemented bythe wireless communication device of FIG. 2.

[0039]FIG. 4 illustrates a schematic block diagram of one embodiment ofthe analog to digital converter 66. In this embodiment, the analog todigital converter is a 2^(nd) order continuous time Delta Sigmamodulator. As shown, the analog to digital converter 66 includes 1^(st)and 2^(nd) gain stages 140 and 144, 1^(st) and 2^(nd) integrators 142and 146, a quantizer 148 and 1^(st) and 2^(nd) digital to analogconverters 150 and 152. As configured, the analog to digital converter66 receives the filtered IF signal 88 and produces a 2-bit digital IFsignal 90. The quantization may be performed at 13 MHz. As one ofaverage skill in the art will appreciate, the quantization rate may varyfrom the 13 MHz as well as the order of the continuous time Delta Sigmamodulator.

[0040]FIG. 5 illustrates an embodiment of the low pass filters 114 and124 and includes a differentiation module and a plurality of cascadedcomb filters to provide the low pass filtering. As one of average skillin the art will appreciate, the number of cascaded comb filters may varyfrom those shown as well as the order of the low pass filter.

[0041]FIG. 6 illustrates a logic diagram of a method for intermediatefrequency to baseband conversion from a single digital IF signal. Theprocess begins at Step 160 where a single digital IF signal thatcorresponds to a modulated RF signal is received. For instance, thesingle digital IF signal may be received from a single analog to digitalconverter that has converted a filtered IF signal into the singledigital IF signal. The filtered IF signal may be produced by a complexbandpass filter that filtered an I and Q component of the modulated IFsignal, which is representative of the modulated RF signal.

[0042] The process then proceeds to Steps 162 and 164. At Step 162, thesingle digital IF signal is mixed with a 1^(st) digital localoscillation to produce a 1^(st) digitally mixed signal. At Step 164, thesingle digital IF signal is mixed with a 2^(nd) digital localoscillation to produce a 2^(nd) digitally mixed signal.

[0043] The process proceeds from Step 162 to Step 166 where the 1^(st)digitally mixed signal is decimation filtered to produce a ₁St basebandcomponent signal. The decimation filtering may be done by low passfiltering the digitally mixed signal to produce a low pass filteredsignal. The low pass filter signal may then be down sampled to producethe 1^(st) baseband signal component.

[0044] From Step 164, the process proceeds to Step 168 where the 2^(nd)digitally mixed signal is decimation filtered to produce a 2^(nd)baseband signal component. The decimation filtering may be done by lowpass filtering the 2^(nd) digitally mixed signal to produce a filteredsignal. The filtered signal is then down sampled to produce the 2^(nd)baseband signal component.

[0045] The preceding discussion has presented a radio receiver thatutilizes a single analog to digital converter, which reduces powerconsumption, reduces integrated circuit size, and provides otherbenefits. As one of average skill in the art will appreciate, otherembodiments may be derived from the teaching of the present invention,without deviating from the scope of the claims.

What is claimed is:
 1. A radio receiver comprises: low noise amplifieroperably coupled to amplify a modulated radio frequency (RF) signal toproduce an amplified modulated RF signal; intermediate frequency (IF)mixing stage operably coupled to mix the amplified modulated RF signalwith a local oscillation to produce a modulated IF signal; complexbandpass filter operably coupled to filter the modulated IF signal toproduce a filtered IF signal; an analog to digital converter operablycoupled to convert the filtered IF signal into a digital IF signal;first digital mixing module operably coupled to process the digital IFsignal with an in-phase digital local oscillation to produce a firstbaseband signal component; and second digital mixing module operablycoupled to process the digital IF signal with a quadrature digital localoscillation to produce a second baseband signal component.
 2. The radioreceiver of claim 1, wherein the complex bandpass filter furthercomprises: a poly phase filter operably coupled to filter an I componentand a Q component of the modulated IF signal.
 3. The radio receiver ofclaim 1, wherein the analog to digital converter further comprises oneof: continuous time delta sigma analog to digital converter; or flashanalog to digital converter.
 4. The radio receiver of claim 1, whereinthe first digital mixing modules further comprises: digital mixeroperably coupled to mix the digital IF signal with the in-phase digitallocal oscillation to produce a first mixed signal; low pass decimationfilter operably coupled to process the first mixed signal to produce adecimated mixed signal; and digital gain control module operably coupledto adjust magnitude of the decimated mixed signal to produce the firstbaseband signal component.
 5. The radio receiver of claim 4, wherein thelow pass decimation filter further comprises: low pass filter operablycoupled to low pass filter the first mixed signal to produce a filteredmixed signal; and down sampling module operably coupled to down samplethe filtered mixed signal to produce the decimated mixed signal.
 6. Theradio receiver of claim 1, wherein the second digital mixing modulesfurther comprises: digital mixer operably coupled to mix the digital IFsignal with the quadrature digital local oscillation to produce a secondmixed signal; low pass decimation filter operably coupled to process thesecond mixed signal to produce a decimated mixed signal; and digitalgain control module operably coupled to adjust magnitude of thedecimated mixed signal to produce the second baseband signal component.7. The radio receiver of claim 6, wherein the low pass decimation filterfurther comprises: low pass filter operably coupled to low pass filterthe second mixed signal to produce a filtered mixed signal; and downsampling module operably coupled to down sample the filtered mixedsignal to produce the decimated mixed signal.
 8. The radio receiver ofclaim 1, wherein the IF mixing stage further comprises: quadrature mixeroperably coupled to produce the modulated IF signal, wherein the complexbandpass filter is centered at the intermediate frequency that is atleast half of bandwidth of the modulated RF signal, and wherein thequadrature mixer in combination with the complex bandpass filter rejectinterference signals at image frequencies.
 9. A method for digitalintermediate frequency (IF) to baseband conversion from a single digitalIF signal, the method comprises: receiving the single digital IF signalthat corresponds to a modulated radio frequency (RF) signal; mixing thesingle digital IF signal with a first digital local oscillation toproduce a first digitally mixed signal; mixing the single digital IFsignal with a second digital local oscillation to produce a seconddigitally mixed signal; decimation filtering the first digitally mixedsignal to produce a first baseband signal component; and decimationfiltering the second digitally mixed signal to produce a second basebandsignal component.
 10. The method of claim 9, wherein the receiving thesingle digital IF signal further comprises: band pass filtering amodulated IF signal to produce a filtered IF signal; and analog todigitally converting the filtered IF signal into the single digital IFsignal.
 11. The method of claim 9 further comprises: adjusting gain ofthe first baseband signal component in accordance with basebandprocessing; and adjusting gain of the second baseband signal componentin accordance with the baseband processing.
 12. The method of claim 9,wherein the decimation filtering of the first digitally mixed signalfurther comprises: low pass filtering the first digitally mixed signalto produce a filtered signal; and down sampling the filtered signal toproduce the first baseband signal component.
 13. The method of claim 9,wherein the decimation filtering of the second digitally mixed signalfurther comprises: low pass filtering the second digitally mixed signalto produce a filtered signal; and down sampling the filtered signal toproduce the second baseband signal component.
 14. An apparatus fordigital intermediate frequency (IF) to baseband conversion from a singledigital IF signal, the apparatus comprises: processing module; andmemory operably coupled to the processing module, wherein the memoryincludes operational instructions that cause the processing module to:receive the single digital IF signal that corresponds to a modulatedradio frequency (RF) signal; mix the single digital IF signal with afirst digital local oscillation to produce a first digitally mixedsignal; mix the single digital IF signal with a second digital localoscillation to produce a second digitally mixed signal; decimationfilter the first digitally mixed signal to produce a first basebandsignal component; and decimation filter the second digitally mixedsignal to produce a second baseband signal component.
 15. The apparatusof claim 14, wherein the memory further comprises operationalinstructions that cause the processing module to receive the singledigital IF signal by: band pass filtering a modulated IF signal toproduce a filtered IF signal; and analog to digitally converting thefiltered IF signal into the single digital IF signal.
 16. The apparatusof claim 14, wherein the memory further comprises operationalinstructions that cause the processing module to: adjust gain of thefirst baseband signal component in accordance with baseband processing;and adjust gain of the second baseband signal component in accordancewith the baseband processing.
 17. The apparatus of claim 14, wherein thememory further comprises operational instructions that cause theprocessing module to decimation filter the first digitally mixed signalby: low pass filtering the first digitally mixed signal to produce afiltered signal; and down sampling the filtered signal to produce thefirst baseband signal component.
 18. The apparatus of claim 14, whereinthe memory further comprises operational instructions that cause theprocessing module to decimation filter the second digitally mixed signalby: low pass filtering the second digitally mixed signal to produce afiltered signal; and down sampling the filtered signal to produce thesecond baseband signal component.
 19. A radio receiver comprises: lownoise amplifier operably coupled to amplify a modulated radio frequency(RF) signal to produce an amplified modulated RF signal; intermediatefrequency (IF) mixing stage operably coupled to mix the amplifiedmodulated RF signal with a local oscillation to produce a modulated IFsignal; complex bandpass filter operably coupled to filter the modulatedIF signal to produce a filtered IF signal; an analog to digitalconverter operably coupled to convert the filtered IF signal into adigital IF signal; and digital processing module operably coupled toproduce a first baseband component and a second baseband component fromthe digital IF signal.
 20. The radio receiver of claim 19, wherein thecomplex bandpass filter further comprises: a poly phase filter operablycoupled to filter an I component and a Q component of the modulated IFsignal.
 21. The radio receiver of claim 19, wherein the analog todigital converter further comprises one of: continuous time delta sigmaanalog to digital converter; or flash analog to digital converter. 22.The radio receiver of claim 19, wherein the digital processing modulefurther comprises: memory operably coupled to the digital processingmodule, wherein the memory includes operational instructions that causethe digital processing module to: mix the digital IF signal with a firstdigital local oscillation to produce a first digitally mixed signal; mixthe digital IF signal with a second digital local oscillation to producea second digitally mixed signal; decimation filter the first digitallymixed signal to produce the first baseband signal component; anddecimation filter the second digitally mixed signal to produce thesecond baseband signal component.
 23. The radio receiver of claim 22,wherein the memory further comprises operational instructions that causethe digital processing module to: adjust gain of the first basebandsignal component in accordance with baseband processing; and adjust gainof the second baseband signal component in accordance with the basebandprocessing.
 24. The radio receiver of claim 22, wherein the memoryfurther comprises operational instructions that cause the digitalprocessing module to decimation filter the first digitally mixed signalby: low pass filtering the first digitally mixed signal to produce afiltered signal; and down sampling the filtered signal to produce thefirst baseband signal component.
 25. The radio receiver of claim 22,wherein the memory further comprises operational instructions that causethe digital processing module to decimation filter the second digitallymixed signal by: low pass filtering the second digitally mixed signal toproduce a filtered signal; and down sampling the filtered signal toproduce the second baseband signal component.